Thanks a lot, I do have the arduino book, but I could not find the answer to my question. You helped me on that!

the basic idea is the arduino can sink or source current, MOST of the time for basic operation the pins are going to provide the positive side, and ground will be negative, but if you set the pins low they are effectively connected to ground.

so positive might run from "somewhere" though your circuit, though the arduino and back to ground. An example of this is the serial communications coming out of the chip, it stays at 5 volts and the arduino drives it down to zero volts to make the appropriate signals.

also do not think of an arduino as a programmable toggle switch, there are limits on how much current it can provide, go beyond those and it will die (though there are ways around that using external hardware)

Yes as this is not actually connected to any processor pin. It will be on all the time. Don't forget the reverse biased diode across the motor. The motor must draw less than the 500mA maximum from the USB supply.

There should be three different pins marked GND. Two of them are going to be on the far left in the strip that's marked, "POWER" and the other pin should be on the far right just below AREF. Every pin on the far left that starts with an A is an analog pin. you can change the voltage that the pins give off. Digital pins 3, 5, 6, 9, 10, and 11 also do the same thing. pins 2, 4, 7, 8, 12, and 13 only put out HIGH or LOW. digital pin 13 has a built in resistor for LEDs so you don't have to use a solderless breadboard to make a cicuit for them. In the POWER strip, Vin is where you put an external power source such as batteries or a solar panel. 5v puts out a steady 5 volts. 3.3v puts out 3.3 volts. I do suggest connecting to Digital Pins 0 or 1. I have not put anything in pin 1, but if you have 5 volts going to the Arduino, DPin 0 should act just like PWR 5v. To see the activity of DPins 0 and 1, look at the built in LEDs that read TX and RE. I do not know what RESET does.